1. Field of the Invention
The present invention pertains to peristaltic pumps and is applicable to linear peristaltic pumps and rotary peristaltic pumps having a section of resilient tubing disposed in between rollers or reciprocal fingers or pushers which progressively radially compress sections of the tubing to pump liquids. More particularly, the present invention pertains to linear and rotary peristaltic pumps which not only radially compress successive sections of resilient peristaltic pump tubing but also axially elongate the peristaltic pump tubing with an adjustable tensioning means to elongate the peristaltic pump tubing to precisely control the cross sectional configuration of the tubing to adjust the flow rate of fluid pumped through the tubing in combination with a means for determining and displaying the speed of the motor operating thee peristaltic pump.
The novel linear and rotary peristaltic pumps constructed in accordance with the invention are particularly applicable to peristaltic pumps having a plurality of flow lines for precisely metering sample liquids to a plurality of samples in a precise and metered volume that are pumped by a peristaltic pump of a linear or rotary peristaltic pump design. The adjustable flow regulation in combination with the display or means for monitoring the speed of the drive motor is particularly advantageous in individually adjusting each of the peristaltic pump flow lines to precisely calibrate a predetermined flow rate or volume from each of the peristaltic pump flow lines to make certain each flow line delivers the same precise metered volume of fluid from each of the flow lines by the individual axial tensioning of each of the peristaltic pump tubing lines and for modifying the rate of flow by varying the speed of a variable speed motor means for driving the peristaltic pump. The axial tensioning of the tubing in conjunction with the speed of a variable speed electric motor imparts important adjustable flow regulation for the precise metering of fluids for applications in medical, biomedical and laboratory applications that require the precise metering and control for the delivery of fluids.
2. Description of the Prior Art
The prior art includes a wide variety of peristaltic pumps which have proved valuable in medical, biomedical and laboratory applications. Peristaltic pumps have been employed particularly advantageously in applications where low contamination and aeration are important considerations and have utilized two basic designs the linear design such as represented by Hemingway, et al, U.S. Pat. No. 4,893,991 and Cannon U.S. Pat. No. 4,728,265 and the rotar peristaltic pumps represented by Tangeman, U.S. Pat. No. 3,403,631, Soderquist, et al U.S. Pat. No. 4,886,431 and Kling U.S. Pat. No. 3,172,367. In both the linear and rotary peristaltic pump designs a section of resilient peristaltic pump tubing is radially compressed along successive sections to provide a pumping action. The linear and rotary peristaltic pump operate upon much the same principal of radial compression propagating axially to transfer and pump fluid from one end of the resilient peristaltic pump tubing to the other end.
The prior art has provided considerably attention in rotary and linear peristaltic pumps to the efficiency of the radial compression of the resilient peristaltic pump tubing with little or no consideration being given to the axial elongation or adjustment to the resilient peristaltic pump tubing to precisely control the amount of fluid being pumped through the peristaltic pump tubing by positioning the ends of the peristaltic pump tubing and providing an axially adjustable elongation means at one or both ends of the section of peristaltic pump tubing to provide for the individual axial elongation of the peristaltic pump tubing between the plurality of reciprocal pushers or fingers or the associated rollers in the rotary peristaltic pump. The prior art has further not provided a display means for carefully monitoring pump motor speed in relation to an axially adjustable elongation means for individually controlling the cross sectional configuration of the peristaltic pump tubing to precisely control the metering and flow of fluid delivered by the peristaltic pump.
In linear peristaltic pumps such as Cannon, U.S. Pat. No. 4,728,265 and Hemingway, et al 4,893,991 a great amount of attention is directed to the radial compression axially along the section of peristaltic tubing without consideration to an axial adjustment of the peristaltic tubing to precisely control the metering of fluids. Considerable attention is similarly given in the design of rotary peristaltic pumps to the radial compression forces exerted on the peristaltic pump tubing by providing various means for adjusting the axial tension exerted on the tubing in the peristaltic pump to vary the radial compressibility of the tubing with little or no consideration given to the axial elongation of the tubing to precisely control flow.
The most pertinent peristaltic pumps prior art appears to be Tangeman, U.S. Pat. No. 3,403,631 which provides levers for indiscriminately tensioning or relaxing all of the peristaltic pump tubing between periods of use and nonuse which indiscriminately elongates all of the tubing at the same time. Tangeman, U.S. Pat. No. 3,403,631 further provides a slot and screw device to permit for the compensation of the permanent stretch which may develop in the tubing after prolonged use but this tensioning device also provides for the substantially indiscriminate elongation of all of the peristaltic pump tubing as opposed to individual elongation and adjustment of each member of the peristaltic pump tubing to control the cross sectional configuration of each member of the tubing to provide for the precise metering or flow of fluids as is done in accordance with the present invention. Tangeman U.S. Pat. No. 3,403,631 further does not provide a display or means for calibrating the elongation of each tube in relation to a particular pump motor speed. Similarly, Kling, U.S. Pat. No. 3,172,367 provides an adjustment for tensioning the peristaltic tubing with respect to the associated rollers of a rotary peristaltic pump but like tangeman 3,403,613 does not individually adjust the axial elongation of each of the peristaltic tubing members to control cross sectional configuration to precisely meter fluids in combination with a pump speed display or monitoring means. As a result, Kling, like Tangeman, does not provide a precise control for the metering of precise volumes of fluid as is done in accordance with the present invention.
Other peristaltic pump prior art such as Ballentine, U.S. Pat. No. 3,402,673 provides a constriction of the ends of the peristaltic tubing to modify flow but does not provide for individually controlling the cross sectional configuration of the tubing by the axial elongation of the tubing to precisely control flow. The peristaltic pump in Thompson U.S. Pat. No. 4,906,168 similarly does not provide a means for axially elongating and adjusting the tension along the length of tubing in the peristaltic pump to precisely meter and deliver precise volumes of liquid pumped through the peristaltic pump. Soderquist, et al U.S. Pat. No. 4,886,431 provides an individual adjustable cartridge assembly for each member of the peristaltic pump tubing but the adjustment provided is for individually increasing and decreasing the radial deforming of the tubing as opposed to the axial elongation and deformation of the peristaltic pump tubing along the length of the peristaltic pump tubing to precisely meter and control flow provided by the peristaltic pump.
As a consequence of the importance of precisely controlling the volume of fluid metered and the control of rate of flow in peristaltic pumps, numerous designs and efforts have been provided in the prior art for constricting, occluding or otherwise providing adjustment for the radial pressure exerted on the peristaltic pump tubing which has not produced an effective, efficient means for metering the precise quantities of small amounts of fluid in peristaltic pumps. In most cases were small accurate quantities of fluid required metering syringes, pipettes and other volumetric or gravimetric devices have been utilized. Despite the importance of peristaltic pumps to medical, biomedical and laboratory applications, prior art peristaltic pumps have not effectively provided a precise metering or control of the flow of fluids with occlusion, constriction or other radial adjustment or control of the peristaltic pump tubing in prior art peristaltic pumps.
The present invention in contrast provides superior control for the precise metering and control of fluids by providing for the axial elongation of the peristaltic pump tubing to control the cross sectional configuration of the peristaltic pump tubing together with a precise monitoring and control of the speed of the peristaltic pump motor which provides far superior metering and flow control characteristics in view of the area upon which control forces are exerted. In a normal peristaltic pump tubing, the cross section of the tubing is small in comparison to the length of the tubing for which the axial elongation adjustment provide a far more sensitive, accurate and precise control of the metering and flow of fluids through the peristaltic pump tubing than can be accomplished through the radial adjustment or occlusion provided in the prior art to vary the radial compressive forces between the plurality of reciprocal pushers or fingers of the linear peristaltic pump or the associated rollers of the rotary peristaltic pump.
As a consequence of the minute variations in the uniformity of the peristaltic pump tubing in internal diameter, tubing wall thickness and resiliency characteristics along the length of the peristaltic pump tubing in conjunction with wear and use it has been difficult to precisely control and meter fluids in peristaltic pumps in critical chemical, biological, medical and laboratory applications which require precise metering of fluids. The axial elongation and adjustment provided by an adjustable tensioning device such as a screw thread process provides for the individually and infinitely adjustable tensioning of the peristaltic pump tubing to provide a precise control of the metering of fluids for use with peristaltic pump tubes of small, internal diameters in linear and rotary peristaltic pumps.
The adjustable axial tensioning means for individually elongating each length of peristaltic pump tubing in combination with the display or other means for controlling the speed of the peristaltic pump motor provides an effective metering system for delivering precise quantities of fluid by controlling the cross sectional configuration of each length of peristaltic pump tubing. The novel arrangement provides a system for the accurate calibration of peristaltic pumps constructed in accordance with the present invention to provide a precise control over the rate of flow in each of the hoses so as to provide a precise metering of fluids in biological, chemical, medical and laboratory uses.